Selective oxidation of glucose to glucuronic acid by cesium-promoted gold nanoparticle catalyst

Gold catalysts outperform palladium and platinum catalysts for the oxidation of sugars with high activity and selectivity toward aldonic acids. The oxidation into other sugar acids, such as uronic and aldaric acids, has been scarcely investigated. Au nanoparticles supported on CeO2 using a soft chemical reduction method with hydrazine, were active for the selective oxidation of low weight carbohydrates (glucose, fructose, maltose) into glucuronic acid. The oxidation occurred in aqueous solution at low temperature using O2 as oxidant and without adding any base. The activity was improved by modifying the supported Au catalyst with cesium, while selectivity was maintained. Under these conditions, high selectivity to glucuronic acid was achieved; however, in the presence of base many by-products were obtained. The preparation of glucuronic acid in high yield using gold catalysts was never reported, which makes the catalyst developed here very interesting for liquid phase oxidation processes.